For all the protocols, straight bone level Straumann dummy implants were planned. The anterior implants were 4.1 × 10 mm, while the posterior implants were 4.8 × 10 mm. The anterior implants were planned to be placed 2 mm subcrestal, while the posterior implants were planned to be placed 1 mm subcrestal.

For the conventional protocols, the clinicians had access to physical intact Nissin model casts that represented ideal tooth anatomy and DICOM images with implant planning. For the FG protocol, the steps were provided by the Dental Wings software, that were followed for each implant placement. This involved pilot drilling, sequential drilling, osteotomy profiling and implant placement. The PG protocol only allowed for pilot drilling short of the planned drill depth. The rest of the steps were completed freehand as per the conventional FH protocol.

All the participants inserted the implants according to the conventional protocol first, followed by the PG and FG protocols. This ensured that clinicians did not practice placing the implants with a guide before the FH protocol implant placement.

For accuracy evaluation of the final implant placement, laboratory scan bodies (ZFX Scan body, ZFX Dental, Zimmer Biomet, Warsaw, IN, USA) were attached to the inserted implants in each polyurethane model. The models with the scan bodies were scanned by a laboratory scanner to generate a virtual model of the cast and implant position. Subsequently, the position of the placed implant was compared against the position of the planned implant at the virtual master model. This was completed by superimposing the final virtual model against the virtual master model by a 3D rendering software (Geomagic Studio, Raindrop, Geomagic Inc., Research Triangle Park, NC, USA). Since the teeth were stable landmarks of all the models, they were used for the superimposition. The superimposition consisted of point-to-point registration followed by automated registration to obtain the best fit between the 2 virtual models. Eventually, each placed implant was spatially related to the planned implant, which allowed for the measurement of the deviation. The deviation of implant position was measured by calculating the following variables: implant vertical deviation, horizontal neck deviation, horizontal apex deviation, and implant angle deviation (Fig. 2).